DELL Mobo/CPU upgrde

[Loryx2000]

I have three older Pentium 4 DELL motherboards: GX260, Dimension 4600 and 4700. From DELL suport I have tried to find out what CPUs those mobos could be upgraded to the max possible performance. Also, the same about RAM. However Dell refused to provide me with this info since they all are out of warranty. I thought maybe anyone had the same ideas and succeded?

 

[dunklegend]

You could replace the motherboards with an AMD one, the new quad core Athlon X4 620 is only $100.

Those motherboards are old anyway, and even an AM2 board will be far more efficient.
Plus you'll probably have a though time with the drivers for those boards.